The head of the Philippines police has said more than 1,900 people have been killed during a crackdown on illegal drugs in the past seven weeks.

Ronald dela Rosa was speaking at a senate hearing into the sharp rise in deaths since Rodrigo Duterte became president.

He said police operations had killed about 750 people, but the other deaths were still being investigated.

Duterte won the presidency with his hard-line policy to eradicate drugs.

He has previously urged citizens to shoot and kill drug dealers who resisted arrest, and reiterated that the killings of drug suspects were lawful if the police acted in self-defence.

He also threatened to "separate" from the UN after it called his war on drugs a crime under international law.

The US has said it is "deeply concerned" by the increase in drug-related killings.

The senate joint inquiry is being conducted by Senator Leila de Lima, who has called on authorities to explain the "unprecedented" rise in deaths.

(CNN)